WO2002072334A2

WO2002072334A2 - Method for producing plastic molded parts using a blowing mold and an injection lance

Info

Publication number: WO2002072334A2
Application number: PCT/AT2002/000082
Authority: WO
Inventors: Rainer Farrag
Original assignee: 'fasti' Farrag & Stipsits Gmbh
Priority date: 2001-03-13
Filing date: 2002-03-13
Publication date: 2002-09-19
Also published as: WO2002072334A3

Abstract

The invention relates to a method for producing plastic molded parts (2) with at least one closed cavity that is delimited by wall parts (3). The outer skin (4) is continuously or discontinuously produced in the shape of a tube and is introduced into a mold cavity (11) of a blowing mold (8) at a temperature located between the plasticizing temperature and the glass transition temperature. The outer skin (4) is placed, at least in areas, against shaping surfaces (12) of the blowing mold (8) by the establishment of a pressure difference between the cavity (5) of the molded part and an outer surface of the same, particularly by means of low air pressure. At least one supply (28) and discharge (58) line is produced between the blowing mold (8) and the cavity (5) of the molded part (2). At least one pressure medium is introduced into the cavity (5) of the molded part (2). The air is removed by suction, at least in areas, between the shaping surface (12) of the blowing mold (8) and the outer surface (13) of the molded part (2) via pores of a porous material that forms the blowing mold (8).

Description

Process for producing molded parts from plastic with a blow mold and an injection lance

The invention relates to a method for producing molded parts made of plastic, an injection lance with a cannula and a blow mold for producing these molded parts, as described in the preambles of claims 1, 2, 11 and 17.

It is already known - according to EP 0 304 885 A2 - to produce molded parts with a closed inner cavity from preforms formed from a plastic material. The plastic blank is introduced into a blow mold formed from several mold halves and the blow mold is closed to form a mold cavity, in particular at the circumferential end edges, whereupon the wall parts for forming the molded part are placed on the mold wall of the blow mold by introducing compressed air or applying a vacuum , A further medium is then introduced or passed through at least one cannula into the interior of the molded part for cooling and dissipating the heat of reaction and partial heat until the hollow body solidifies. A disadvantage of such processes is that only a certain spatial shape of molded parts can be industrially produced in large series using such processes.

The present invention has for its object to provide a method, an injection lance with a cannula and a blow mold, with which it is possible to create an industrially repeatable, secure, high-volume process with little waste and various devices or system parts with which blow molded parts of this type, the outer skin of which can have a wide variety of wall thicknesses, can be produced.

The object of the invention is achieved by the method according to claim 1. It is advantageous here that it is now possible to produce blow molded parts which can have widely differing dimensions in the mutually angular spatial directions in a ratio of, for example, length 2000 mm, width 600 mm and thickness 5 to 20 mm. As a result, it is now possible to extract air from the cavity in partial areas of the mold surface of the blow mold via the porous and porous material, since the wall parts on the mold surfaces in a fixed position between the outer surface of the object and the mold surfaces with a correspondingly high negative pressure be held opposite the molding surface. This almost immovable positioning makes it possible lent to pierce the wall parts placed on the mold surfaces with the injection lance or its cannula and thus to prevent a relative displacement of the wall part relative to the cannula during the further shaping towards the molded part.

The object of the invention is also achieved independently by the measures according to claim 2. It is particularly advantageous that several injection lances can be pushed through the wall parts held opposite the molding surface, whereupon a pressure builds up in the interior of the molding, that is to say in its cavity, for a certain period of time and the wall parts are thus brought into contact with the molding surfaces and after establishing the tightness for more rapid heat dissipation, another liquid medium is introduced into the cavity and passed through it. In this way, on the one hand, a uniform compressive force is achieved on the wall parts in the direction of the mold surfaces of the blow mold and, on the other hand, the amount of heat supplied therein during the softening process is rapidly dissipated from the interior due to the high heat absorption capacity.

Furthermore, a procedure according to the measures specified in claim 3 is advantageous because an even higher pressure difference can thereby be built up between the cavity or the interior of the molded part and the outer surface and, as a result, a richer installation and faster shaping of the molded part can take place.

Another advantageous procedure is described in claims 4 and 5, which makes it possible to quickly determine leakage losses without environmental pollution and pollution of the blow mold and also to be able to achieve adequate shaping and, if appropriate, cooling.

A variant of the method according to claim 6 is also advantageous, because as a result a higher amount of heat can be dissipated more quickly from the interior and the cycle times can thereby be additionally shortened.

Further advantageous procedures are characterized in claims 7 and 8, since the heat can be dissipated more quickly because of the high temperature difference between the material of the molded part to be produced and the liquid pressure medium introduced into the cavity.

A procedure according to the features in claim 9 is also advantageous, since it results in a otherwise the subsequent connection process can be saved and, at the same time, after removal of the molded part, it is suitable for installation without further work steps.

Due to the procedure as described in claim 10, the cavity can be filled quickly and safely due to the different specific weights of the two print media.

Irrespective of this, the object of the invention can also be achieved by the injection lance according to the features specified in claim 11. It is advantageous that there is always a sealing contact between the wall parts of the molded part and the cannulas penetrating them, so that leakage of the cooling or pressure medium from the cavity of the molded part in the direction of the outer surface thereof can be prevented in a secured manner. Due to the conically tapered sealing surface between the cannula and the passage opening formed in the wall part, there is always a secure contact force between the wall part and the cannula in the area penetrating it, on the one hand due to the adjusting force applied to the cannula and on the other hand due to the pressure prevailing in the cavity of the molded part ,

A further embodiment according to claim 12 is also advantageous because, as the cannula passes through the tough plastic material of the wall part, the latter is only displaced in the area around the cannula and the displaced mass increases the contact force of the wall part on the outer surface of the cannula causes.

Another advantage is an embodiment according to claim 13, with which both the supply and the discharge of the pressure medium into or from the cavity of the molded part can take place immediately adjacent to one another and the required amount of coolant or pressure medium can also be adapted to the volume of the cavity ,

Due to the needles arranged in pairs and concentrically to one another, as is characterized in claim 14, both the supply and the discharge of the pressure medium can advantageously take place in or out of the cavity of the molded part in the smallest space.

Due to the design according to claim 15, it is possible to achieve a different inflow direction into the cavity of the molded part depending on the selected pressure medium. According to another embodiment variant, a direction of supply of the gaseous or liquid pressure medium into the cavity of the molded part is achieved in the same direction.

However, the object of the invention is also independently achieved by the features of claim 17. The advantages resulting from the combination of features of the characterizing part of this claim lie in the fact that the arrangement or formation of partial areas of the mold surface or parts of the entire blow mold means that the air present between the outer surface of the object and the mold surface is sucked off without additional drilling or openings can take place and so a large area of the wall part can be easily done in these areas. The holding or fixing force of the outer surface relative to the mold walls of the mold cavity can be determined by the choice of the level of the negative pressure in order to achieve an almost or completely immovable positioning. This prevents a relative adjustment or displacement of those wall parts relative to the mold surfaces of the blow mold.

In the embodiment according to claim 18 or 19, it is advantageous that the injection lances push the molded part through in those areas of the molded part which are not of great importance in terms of their strength properties and optical properties for the overall formation of the molded part.

With the design according to claim 20 or 21, it is possible to form large-area molded parts in relation to the edge regions which, with sufficient strength, in particular high bending and torsional strength, have a low weight.

Finally, the configuration according to the features of claims 22 or 23, in particular in the area of the injection lances, enables the wall parts to be positioned almost immovably in relation to the mold cavity before the injection lances penetrate it.

The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawings. Show it:

Figure 1 shows a plant for the production of molded parts in side view and simplified, schematic representation.

Figure 2 shows a partial area of the plant on an enlarged scale, partially in section and a simplified, schematic representation.

Fig. 3 shows a molded part produced with the system in a simplified, perspective

Presentation;

4 shows a partial area of the injection lance in the passage area through a wall part of the molded part;

5 shows a further partial area of another injection lance in the passage area through a wall part of the molded part;

6 shows a partial area of a further injection lance in the passage area through a

Wall part of the molding;

7 shows another embodiment of a blow mold cut in a side view and a simplified, schematic illustration;

8 shows a further embodiment of a blow mold in a side view, in section and in a simplified, schematic representation;

9 shows a further partial area of another injection lance in the passage area through a wall part of the molded part.

As an introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, and the disclosures contained in the entire description can be applied analogously to the same parts with the same reference numerals or the same component names. The position information selected in the description, such as, for example, top, bottom, side, etc., are also related to the figure described and illustrated immediately in the event of a change in position, to be transferred accordingly to the new position. Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent independent, inventive or inventive solutions.

1 and 2 show a simplified system 1 or a partial area thereof for the production of molded parts 2 made of plastic, in particular of flat panels, shelves, bumpers, table tops and much more, which may include at least one of wall parts 3 have multilayered outer skin 4 and closed cavity 5.

The system 1 usually comprises an extruder 6, in which the raw material or the raw materials for the formation of the plastic are prepared and then brought into a preform by an extrusion tool 7. A rough definition of the outer skin 4 is achieved by the extrusion tool 7, the outer skin preferably being produced in a tubular manner continuously or discontinuously. After the preform has left the extrusion die 7, it has a temperature between the plasticizing temperature and the glass transition temperature of the respective material, this being dependent on the material used. This temperature range can also be limited to the extent that this range is reduced by a temperature based on the plasticizing temperature between 1 ° C and 50 ° C to 80 ° C and based on the glass temperature between 1 ° C and 50 ° C to 80 ° C is increased.

However, it is of course also possible to form the outer skin 4 or its wall parts 3 from a flat preform and then to subsequently shape it into the desired shape of the preform, in order to be able to subsequently carry out the further shaping.

Furthermore, the system 1 also includes a simplified blow mold 8, which in the present exemplary embodiment is formed by two simplified molded part halves 9, 10. Of course, it is also possible to assemble the blow mold 8 from several components, it being essential that within the blow mold 8 after the individual molded part halves 9, 10 or more of these parts have been closed, they delimit a mold cavity 11 which is sealed off from the external environmental conditions. This mold cavity 11 is delimited by one or more mold surfaces 12 within the blow mold 8. In the exemplary embodiment of the system 1 shown here, the blow mold 8 is designed as a so-called standing mold, ie the preform emerging from the extrusion tool 7 is preferably produced in a vertical direction, falling from top to bottom, so that due to its own weight no bending and Shear stresses are introduced into the preform. It should be mentioned that the system parts, in particular the extruder 6 and the extrusion tool 7, can be freely selected and designed according to the prior art. For the sake of clarity, known guides, adjustment mechanisms, locking and holding devices and supply devices, which are not essential to the invention, have been omitted in the representation of the blow mold 8.

According to the known prior art, in the manufacture of flat panels which delimit a cavity by their outer skin, the procedure is such that they are introduced into the blow mold and after the closure thereof the cavity of the molded part or panel is filled with air and the pressure within of the cavity is maintained until the molded part has cooled to such an extent that the molded part has cooled down so far that it is dimensionally stable and can be removed from the mold cavity of the blow mold 8. In this known process, the surface can be twisted very easily, which means that the cooling process must be coordinated accordingly and, depending on the mass to be cooled, a large amount of time, e.g. 15 to 30 min is required.

In the exemplary embodiment shown here in FIG. 2, the molded part 2 is arranged in a position within the mold cavity 11 in which the individual wall parts 3 are brought into contact with the individual molded surfaces 12. Before the preform is introduced into the mold cavity 11 with the blow mold 8 open, the latter has a temperature between the plasticizing temperature and the glass transition temperature of the respective material. This temperature range can also be limited in that this range is reduced by a temperature based on the plasticizing temperature between 1 ° C and 50 ° C to 80 ° C and increased based on the glass temperature between 1 ° C and 50 ° C to 80 ° C becomes. Subsequently, the outer skin 4 is brought into contact, at least in some areas, with the molded surfaces 12 of the blow mold 8 by building up a pressure difference between the cavity 5 of the molded part 2 and an outer surface 13 thereof. This can be done in that a lower pressure than the cavity 5, in particular a pressure below the atmospheric air pressure, is generated between the outer surface 13 and the molded surfaces 12 and the desired system is thus carried out. Furthermore, it is shown here in a simplified manner that after the blow mold 8 has been closed, the cavity 5 of the molded part 2 is brought into line connection with lines 14, 15. In the embodiment shown here in FIG. 2, for a first pressure medium which is formed by a gas, in particular air, the line 14 is arranged in an upper region of the blow mold 8 and the line 15 in a lower region and opens into the Cavity 5. This makes it possible to introduce the pressure medium through the line 14 into the cavity 5 and, if necessary, to let it flow out of the cavity 5 via the line 15. The pressure build-up within the cavity 5, on the one hand, exerts a uniform pressure on the still deformable outer skin 4 until it is brought into contact with the mold surfaces 12 and, on the other hand, a corresponding air throughput, by means of which additional cooling can be achieved if necessary. It is of course possible to assign several of these lines 14, 15 to the cavity 5, this being dependent on the throughput or the flow volume per unit of time.

In the embodiment shown here, the lines 14, 15 are each in the transition or. Edge area between the mostly parallel to each other wall parts 3 arranged. It is of particular importance that those wall parts 3 of the molded part 2 which are to be penetrated by the lines 14, 15 after the blow mold 8 has been closed are already held or fixed in their position and position on the molded surfaces 12 in such a way that a this wall parts 3 are almost immovably in contact with the shaped surfaces 12. Only after the exact fixation and shape fixing is it possible to pierce or penetrate through injection lances 16 described later in detail.

This secure installation or fixation of the individual wall parts 3 can be achieved in that at least partial sections of the blow mold 8 are formed from a porous material. In particular, this can be a sintered metal, pores 17 being shown here in a simplified and enlarged manner in the region of the lines 14, 15. The arrangement of a large number of these pores 17 now makes it possible for the entire blow mold 8 to be introduced in a housing 18, which is shown here in a simplified manner and which is sealed airtight against the external ambient conditions, and for the interior of the housing 18 to have a schematically illustrated vacuum unit 19, which can optionally be connected to a regulating and / or control device, is lowered to a pressure which is lower than the external air pressure, through which the pores 17 suck off the air contained between the outer surface 13 and the molded surfaces 12. Through the use of the porous material described above to form the blow mold 8, but of course also the Entire blow mold 8 can be formed from this material, a pressure difference can be built up in relation to the cavity 5 of the molded part 2 and thus the individual wall parts 3 can be brought into contact with the mold surfaces 12 without a change in pressure in the cavity 5 being necessary.

Only individual subsections of the blow mold or blow mold halves 9, 10 and, if appropriate, the entire blow mold 8 can be formed from this porous material having pores 17. This allows a large-area air extraction from the previously described space through the plurality of pores 17, whereby a relatively large holding or fixing force between the wall parts 3 and the molded surfaces 12 can be achieved in these areas.

If these predeterminable wall parts 3 are now held fixed on the shaped surfaces 12, the injection lances 16 can be pushed through the wall parts 3 and their ends inserted into the cavity 5 of the shaped part 2. Now the gaseous pressure or cooling medium is introduced into the cavity 5 via at least one line 14 and a pressure between 1.5 bar and 50 bar, preferably between 2 bar and 7 bar, is built up, the same being discharged through at least one line 15 , Thus, on the one hand, a compressive force is applied to the wall parts 3 and, on the other hand, heat is dissipated from the cavity 5 by flowing through. This filling process and the associated shaping process can take place over a period of between 0.01 seconds. and 60 sec., preferably between 0.01 sec. and 10 seconds. Subsequently, an outflow of the gaseous medium via the line 15 is prevented and the pressure in the cavity 5 is kept almost constant within the limits described above. The introduced gaseous pressure or cooling medium has a temperature between 35 ° C. and 0 ° C., preferably between 25 ° C. and 10 ° C., before it is introduced into the cavity 5.

After reaching the built-up and predeterminable pressure in the cavity 5, a further supply is prevented and this pressure over a period of between 1 sec. and 5 min. is monitored, and when a constant or only minimally decreasing pressure is determined, a liquid medium is then introduced into the cavity 5 through the lines 14, 15 via at least one injection lance 16, with excess pressure being built up, and conveyed through the latter. The supply takes place via the line 15 shown below, whereby the cavity 5 is filled in the direction of the further line 14 - which is shown here above. This creates the liquid medium a pressure between 1.5 bar and 50 bar, preferably between 2 bar and 6 bar within the cavity 5, with rapid heat dissipation from the molded part due to the temperature difference between the molded part 2 to be cooled and the liquid pressure medium introduced as a result of the higher heat absorption capacity 2 towards the liquid pressure or cooling medium.

Due to the fact that the molded parts, e.g. Panels can usually have an areal extension of up to 1 m by 2 m and a wall thickness between 0.1 mm and 30 mm, the distance between the parallel and directly facing wall parts 3 is relatively small and is between 0.5 mm and 70 mm, preferably between 5 mm and 50 mm. The cavity 5 has a relatively large area in terms of area with a small flow cross section.

Furthermore, it is also possible to arrange sections or bridges or reinforcing ribs in the cavity 5 between the mostly parallel wall parts 3 which are large in area, as is shown in simplified form in dash-dotted lines in FIG. 2. Attention must be paid to an alignment and arrangement such that an almost unimpeded flow between the supply and discharge lines within the cavity 5 is ensured. It is therefore advantageous if the longitudinal extension of the webs or reinforcing ribs runs in a direction between the supply and discharge lines or with a minimal angular deviation from it.

This results in the filling and the rapid heat dissipation as a result of the cross-sectional design of the cavity 5 between the lines 14, 15, the supply through line 15 and the discharge through line 14 taking place during the filling with a liquid pressure or cooling medium, to coordinate exactly with each other. The liquid cooling or pressure medium is advantageously formed by water, optionally with additives, the liquid cooling or pressure medium being brought to a temperature of below 20 ° C., preferably to 5 ° C. or before being introduced into the cavity 5 of the molded part 2 for example between -10 ° C and -50 ° C, preferably between -20 ° C and -40 ° C, is cooled. The cooling or pressure medium can contain or be formed by a refrigerant.

Due to the staggered or simultaneous introduction of the different pressure or Cooling media in the cavity 5 of the molded part 2 is a pressure difference between the outer surface 13 of the molded part 2 and the molded surfaces 12 of the blow mold 8, the pressure prevailing in the cavity 5 being higher than the pressure between the outer surface 13 and the molded surfaces 12 of the blow mold 8.

Furthermore, during the production process for the molded part 2, it is still possible to insert or insert a single-layer and / or multi-layer layer 20 into the mold cavity 11 at least in regions before closing the blow mold 8 and to the outer surface 13 of the molded part 2 during its final shaping to form, as is simply indicated by dashed lines. This can be done in a wide variety of ways, and adhesion due to the still viscous plastic material for forming the molded part 2 can be achieved with sufficient adhesive force after cooling. However, it is also possible to coat the layer 20 at least in regions on the surface facing the outer surface 13 with an adhesion promoter and / or an adhesive in order to enable the adhesion process or the molding process or to achieve a sufficient level of force.

Furthermore, a possible embodiment of a supply system 21 is shown in simplified form in FIG. 2, with which the previously described processes or process steps, in particular the supply and discharge of the two different pressure or cooling media into and out of the cavity 5 of the molded part 2 , can be carried out. Through the use of the two different pressure or cooling media, it is of particular importance that, as has also been described above, when using the liquid cooling or pressure medium in the penetration area of the injection lances 16 through the wall parts 3 of the molded part 2 there is a liquid-tight or watertight closure of the cavity 5 with respect to the mold surfaces 12 of the blow mold 8 and thus to prevent the liquid cooling or pressure medium from escaping from the cavity 5 in the direction of the blow mold 8.

This would lead to a pressure drop within the cavity 5, and additionally, as has also been described above, the porous choice of the material for the blow mold 8 also allows the liquid cooling or pressure medium to penetrate into the blow mold in this area 8 would take place and thus a loss of the internal pressure and the associated cooling or pressure medium would go hand in hand. Likewise, an exit of the liquid cooling or pressure medium from the blow mold 8 to the surroundings is also associated therewith. In this supply system 21, at least two pressure or supply circuits are provided for supplying the blow mold 8, namely one for the gaseous or air-shaped pressure or cooling medium and another for the liquid pressure or cooling medium. That circuit for the gaseous pressure or cooling medium serves to initially inflate the preform introduced into the mold cavity 11 to form the molded part 2 and thus to mold it. During this phase of the process, the preform should not be cooled too much so as not to unnecessarily complicate the shaping from the preform to the molded part 2, since the colder the preform becomes, the pressure forces for shaping would have to be increased significantly. The air flow supplied through the line 14 keeps the molded part 2 under pressure until the molded part 2 is finally formed and an outer peripheral layer is correspondingly hard enough to be able to reduce the pressure in the interior 5, without thereby causing any subsequent deformation of the molded part 2 takes place.

After this shaping process has ended, the gaseous cooling or pressure medium is released to the atmosphere through line 14, the liquid cooling or pressure medium being supplied to cavity 5 at the pressures previously described through this line 15 during this discharge process. As a result of this supply process, the air still in the cavity 5 is pressed upward and discharged from the cavity 5 through the line 14. After all the air has escaped and the water has filled the entire cavity 5, the water pressure is maintained until the entire molded part 2 can be cooled and removed from the blow mold 8. It can be advantageous if a correspondingly high mass of plastic material has to be cooled, to convey the liquid cooling or pressure medium through the cavity 5 with a corresponding pressure and thus to achieve sufficient heat dissipation within a shorter time, thereby reducing the cycle times for the production of the molded part 2 can be significantly reduced.

After the molded part 2 has been sufficiently cooled by the liquid cooling or pressure medium and is dimensionally stable, the gaseous cooling or pressure medium, in particular air, is in turn introduced into the cavity 5 under pressure through the line 14, whereby a line 15 opens after opening The liquid cooling or pressure medium can flow out of the cavity and the entire cavity 5 is in turn emptied. Once this emptying process has been completed, the blow mold 8 can be opened and the molded part 2 can be removed. A possible embodiment of the supply system 21 is shown schematically in simplified form in FIG. To generate the gaseous pressure build-up, the supply system 21 has a pressure generator 22 which is in line connection with the two lines 14, 15. In each of the two lines 14, 15, starting from the pressure generator 22, a check valve 23, 24 and a further control element 25, 26, for example in the form of a shut-off valve, are arranged. The two check valves 23, 24 can be set to a predeterminable operating pressure at which it is only possible for the generated compressed air to flow through from the pressure generator 22 to the lines 14, 15. As already described above, for the first pressure circuit, starting from the pressure generator 22, the pressure medium is conveyed through the check valve 23 and the actuator 25, which can be formed, for example, by a shut-off valve, into the line 14 and further into the cavity 5.

To set up the previously described further pressure circuit for the liquid pressure or cooling medium, the supply system 21 has a further pressure generator 27, for example a high-pressure pump, which is in flow connection with the line 15 via a feed line 28 and with the interposition of a further actuator 29. An overflow line 31, which is in flow connection with a storage device 32, is provided between the feed line 28 and the actuator 29 with the interposition of a relief element 30. The pressure generator 27 is also in flow connection with the storage device 32, which makes it possible to remove the liquid cooling or pressure medium from the latter and to feed it from the supply line 28 to the line 15. If a predetermined pressure is exceeded within this line connection, a return of the liquid cooling or. Pressure medium in the storage device 32, so that when the pressure is constantly built up by the pressure generator 27, the predetermined line pressure cannot be exceeded.

Furthermore, the storage device 32 can also be assigned a cooling device which, in accordance with the known prior art, the cooling or. Cools the pressure medium to a predeterminable temperature before it is fed into the cavity 5 or which dissipates the amount of heat already removed from the molded part 2 here. In this case, the storage device 32 can also be surrounded with insulation in order to prevent heat absorption from the surroundings. It should be mentioned that this cooling device according to the known prior art can be realized by any choice of components.

The line 14 is further interposed with a further control element 33 with a further line 34 which is in turn connected to a further line 35 and which is subsequently in flow connection with the storage device 32. This previously described line connection serves to return the liquid cooling or pressure medium of the storage device 32 which is passed through the cavity 5, it being possible to provide a filter element 36 within this line connection, which can preferably be arranged immediately before the return to the storage device 32 in order to separate possible contaminants contained in the recirculated liquid pressure or coolant quantity and thus to prevent blockage or displacement of flow or passage cross sections. The line 35 is also in line connection with the line 14, and a further relief member 37 can additionally be provided in this line 35. During the filling of the cavity 5 with the liquid cooling or pressure medium, this relief member 37 serves to be able to discharge the air flowing out of the cavity 5 to the environment via the line 14 under a predeterminable pressure.

Furthermore, a return line 38 is provided, which is in flow connection on the one hand with line 15 and on the other hand with line 35 and optionally line 34. This return line 38 opens into the line 15 in the region of the two actuators 26, 29, a further actuator 39 being provided within the return line 38.

If a corresponding pressure is now built up via the pressure generator 22 and flow through the closing elements is prevented in the actuators 26, 29 and 39, the non-return valve 23 and the actuating element 25 flow into the line 14, as is indicated schematically by an arrow , Thereupon, the cavity 5 of the molded part 2 is filled to the predeterminable pressure, the measuring elements 40, 41 assigned to the two lines 14, 15 being able to determine the pressure prevailing in the cavity 5. If the pressure within the lines 14, 15 and the cavity 5 is kept at an almost constant value without any further supply by the pressure generator 22, this is a sign that the cavity 5 of the molded part 2 is airtight against the external environment, whereby the tightness in the area of the injection lances 16 is of particular importance here. If this pressure remains almost constant, the blow molding 8 cools the molded part 2 until it is dimensionally stable in the area of its outer surface 13 so that the liquid cooling or pressure medium can be supplied to the cavity 5 from the storage device 32 , Now, since the tightness is ensured, a flow connection to line 15 can be established starting from the storage device 32 via the pressure generator 27, the supply line 28 and the actuator 29 and the liquid cooling or pressure medium can be supplied to the cavity 5 via this. Via the line 14 and the relief member 37, the air in the cavity 5 is discharged, this being done until the cavity 5 is completely filled with water and when a predetermined pressure is reached, the return and flushing of the cavity 5 with the liquid pressure or cooling medium takes place to the storage device 32. This process is continued until sufficient cooling of the molded part 2 has been achieved. Subsequently, this flow-through process is ended and, in turn, starting from the pressure generator 22, the gaseous pressure or cooling medium is fed to the cavity 5 via the line 14, as a result of which the liquid pressure or cooling medium still located in the cavity 5 is fed via line 15, the actuator 39 and the return line 38 and line 35 of the storage device 32 is returned. This continues until the cavity 5 is almost completely or completely emptied. If a pressure loss is determined during the pressure test when the cavity 5 is filled with the gaseous cooling or pressure medium, no liquid cooling or pressure medium can be introduced into the cavity 5 and the cooling process is carried out only with the gaseous cooling or print media.

To compensate for possible leakage losses, it is possible to assign an additional unit 42 to the storage device 32 for the liquid cooling or pressure medium, with which such losses can be compensated for. This addition or refill is to be set up as required.

In the cooling process described above, due to the heat absorption capacity inherent in the liquid cooling or pressure medium, in particular water, it is possible to cool with a relatively small amount of material and still drastically shorten the cycle times. It should be noted that an evaporation process is brought about by the liquid cooling medium introduced into the cavity 5 as a result of the still high temperature of the molded part 2, as a result of which a rapid rise in pressure in the line 14 and the relief member 37 must be compensated for. The higher the pressure increase in line 14, the more this leads more quickly to an evaporation of the liquid cooling or pressure medium at the beginning of the supply, as a result of which the regions of the wall parts facing the cavity 5 are rapidly cooled. The faster the supply via the line 15 into the cavity 5, the lower the steam development in the cavity 5, but due to the amount of heat supplied to the liquid cooling or pressure medium, this can be quickly removed from the molded part 2.

FIG. 3 shows a molded part 2 shown in simplified form, in which the layer 20 described above is arranged in the region of its outer surface 13, at least in regions. This layer 20 can be formed in one or more layers and can be formed, for example, by fabric, knitted fabric, woven fabric, fleece, scrim, carpet and much more. However, layers of any other material can also be molded onto it, here, for example, decorative elements or layers with higher strength properties can be used.

4 to 6 different designs and possible uses of the injection lance 16 are shown, the same reference numerals being used for the same parts as in the previous FIGS. 1 to 3. These injection lances described here in the figures can be combined with one another in a wide variety of ways and can be assigned to the blow mold 8 in any arrangement and design.

4, the injection lance 16 has a cannula 43, which is shown in a position in which an end 44 facing the cavity 5 projects through the wall part 3 of the molded part 2 and thus a flow connection with the cavity 5 is possible. In this embodiment shown in FIG. 4, the end 44 is designed in the form of a cone which closes the cannula 43 with the channel 45 arranged therein, openings 47 being arranged in a cannula wall 46 in the area facing the end 44, through which openings the gaseous or liquid cooling or pressure medium can flow into the cavity 5. The openings 47 form outlet openings for the cooling or pressure media from the injection lance 16. This channel 45 is in flow connection with one of the two lines 14, 15 shown in FIG. 2. The arrangement and number of the openings 47, in particular their cross section, depends on the quantities to be introduced into the cavity 5 and is to be switched off accordingly.

5 shows another design of the injection lance 16 in the region of the end 44. provided, in contrast to the embodiment shown in FIG. 4, the cannula 43 has an end face 48 which extends obliquely with respect to its longitudinal extent and which is thus tapered at one end. This in turn allows simple penetration of the wall part 3 and the full cross section of the channel 45 is available as an outflow opening when it flows out.

6 shows a further embodiment of the injection lance 16, in which the end of the cannula 43 is again shown in a position in which there is a flow connection with the cavity 5 of the molded part 2. In this exemplary embodiment shown here, the injection lance 16 has a push piston in addition to the cannula 43

49, which is penetrated by the cannula 43.

The thrust piston 49, as is indicated schematically by a double arrow, can be adjusted in the blow mold 8 in the direction of the cavity 11 and in the direction away from it by means of a drive (not shown in more detail). The thrust piston 49 has a sealing surface 50 on the side facing the mold cavity 11, which is shown here in a position flush with the mold surface 12. Due to the possible adjustment movement within the blow mold 8, a relative displacement of the sealing surface 50 with respect to the mold surface 12 is possible, which allows penetration into the film cavity 11 and thus an increased contact pressure in the area of the injection lance 16 on the wall part 3 can take place. As a result, however, any other desired position relative to the shaped surface 12 can also be preset or readjusted.

In addition, it is also shown here that a groove-shaped recess 51 can be arranged recessed in the sealing surface 50, which is preferably designed to run continuously around the cannula 43. This recess 51 can be connected via a suction line 52 to a vacuum generator (not shown here), which means in the area of the sealing surface

50 between this and the outer surface 13 of the wall part 3, an additional holding or fixing can take place.

The cannula 43 is here in the thrust piston 49 also relative to this and the blow mold 8 from a position outside the mold surface 12 of the mold cavity 11 in a rest position into this projecting into the mold cavity 11 by means of a drive, not shown, adjustable. This makes it possible to pierce the wall part 3 in the area of the injection lance 16. It is also shown here that the cannula 43 in the end 44 facing the film cavity 11 over a distance 53 in the direction of the longitudinal extent of the cannula 43, starting from the area facing the molding surface 12 in the direction of the end 44, is conically tapered by an angle 54.

The end 44 can, as shown here, be formed tapering from the cannula walls 46 to a longitudinal axis 55. However, it is of course also possible to design the end configurations of the cannula 43 according to the embodiments as has been shown and described in FIGS. 4 and 5. It is essential in all of the previously described configurations of the injection lances or their cannulas 43 that a sealing contact between these two parts takes place between an outer surface thereof and the penetrated wall part 3 in the area of the passage opening, so as to allow the liquid cooling or To prevent print media.

Of course, it is also possible to connect the cannula 43 to the thrust piston 49 to form a unit or to form it from a single component, as a result of which only a common adjustment of the thrust piston with the cannula 43 is possible.

It is essential in the embodiment according to FIG. 6 that the end face or sealing surface 50 of the thrust piston 49 surrounding the cannula 43 is designed as an annular surface and this serves as a sealing surface between the outer surface 13 of the molded part 2 and the thrust piston 49. It is independent of whether the thrust piston 49 forms a unit with the cannula 43 or whether these two previously described components are additionally adjustable relative to one another in the longitudinal direction of the cannula 43.

An outer dimension 56, in particular a diameter of the cannula 43, is between 0.5 mm and 100 mm, preferably between 1.0 mm and 80 mm, depending on the volume of the cavity 5 of the molded part 2. The amount of gaseous and / or liquid cooling or pressure medium to be supplied per unit of time is dependent on this volume, the inflow cross section into the cavity 5 in conjunction with the supply pressure influencing the filling and cooling time.

Of course, it is also possible to provide the groove-shaped recess 51 described in FIG. 6, preferably around the cannula 43 of the injection lance 16, also in the embodiments described in FIGS. 4 and 5 and with the suction line 52, likewise not closer to one here shown vacuum generator and optionally one To connect a control and / or regulating device, as a result of which the wall part 3 can also be fixed or held in this area surrounding the cannula 43 between the molded surface 12 and the outer surface 13 of the molded part 2. However, this also makes it possible, for example, to extract possible leaks and, if appropriate, the gaseous or liquid pressure medium escaping through the wall part 3 in the puncture region of the cannula via the suction line 52 from the mold cavity 11.

7 and 8 show further and possibly independent designs of the blow mold 8, again using the same reference numerals as in the previous FIGS. 1 to 6. Of course, the previously described embodiments of the blow mold 8, the supply unit 21 and the design of the injection lances can

16 can be combined and used in many different ways. In the case of these embodiments shown here, reference is made in particular to the fixing options for the wall parts 3 of the molded part 2 in the region of the molded surfaces 12, the blow moldings 8 being shown in the closed position and with the molded part 2 removed for the sake of clarity.

As already described above, partial sections or partial areas of the blow mold 8 can be formed from the porous, in particular air-permeable material. In the embodiment example shown in FIG. 7, both mold halves 9, 10 are made of porous and porous

17 formed material or material, again the entire blow mold 8 is arranged in the airtight housing 18 and the interior of the housing

18 can be connected to the vacuum unit 19 and, if appropriate, to a regulating and / or control device assigned to the supply system 21. From the supply system 21, the two lines 14, 15 for the supply and discharge of the gaseous and / or liquid cooling or pressure media into the cavity 5 of the molded part 2, as shown in FIG. 2, are shown only schematically.

For the necessary fixation and almost immovable mounting of the wall part 3 in the area of the cannula 43 of the injection lance 16, the area of the blow mold 8 surrounding the cannula 43 is airtightly delimited from the other components of the blow mold 8 by a schematically illustrated insert part 57, this insert part 57 also a schematically indicated derivative 58 is in line connection, which also passes through the housing 18 or its interior, it being essential that between the interior of the insert 57 and the derivative 58 there is no line connection with the interior of the housing 18 prevails. As a result, it is now possible to suck and fix the wall part 3 before it pierces through the cannula 43 in the area within the insert part 57 on the molding surface 12 by generating a vacuum, and then to pierce the wall part 3 in this area through the cannula 43 in order to be able to establish a line connection with the cavity 5.

In order to achieve an even better and faster contact of the further wall parts 3 of the molded part 2 with the further mold surfaces 12 within the mold cavity 11, the other parts of the blow mold 8, which are also formed here from the porous material, can be produced by the interaction of the vacuum unit 19 sucked off with the housing 18 the remaining air present between the outer surface 13 of the molded part 2 and the molded surfaces 12 and a corresponding negative pressure is built up. This suction process can take place before the gaseous pressure or cooling medium is introduced into the cavity 5 of the molded part 2 and / or simultaneously.

8 again shows the blow mold 8 with the two molded part halves 9, 10, with the mold cavity 11 again being shown with the molded part 2 removed for the sake of clarity.

The cannulas 43 of the injection lances 16 are again in the working position, i.e. in the position in which the wall part 3 of the molded part 2 protrudes and a line connection with the cavity 5 is shown. The adjustment of the cannula 43 or the injection lance 16 from the rest position lying outside the mold cavity 11 delimited by the mold surface 12 into an insert position projecting into the mold cavity 11 at least by the thickness of the outer wall of the molded part 2 to be produced is carried out with an adjusting drive, not shown here, which can be chosen freely according to the state of the art.

In the exemplary embodiment shown in FIG. 8, the blow mold 8 is formed from the molded part halves 9, 10, which in turn can be composed of several parts to form the molded part halves. In the vicinity of the cannulas 43 of the injection lances 16, the molded part half 10 shown here is again formed by the previously described porous material with the pores 17, this area being again delimited airtightly from the other parts of the blow mold 8 by insert parts 57. Due to the arrangement of the entire blow mold 8 within the housing 18 and the associated vacuum Unit 19 can in turn those sub-sections or sub-areas of the blow mold 8, which are formed by the porous material having the pores 17, are connected to the interior of the housing and that area within the mold cavity 11 can be suctioned off.

In this exemplary embodiment, these are again the areas which are assigned to the injection lance 16. For example, only the immediate area around the injection lance can be formed by the porous material, or the entire part that forms over the edge area and a narrow side of the molded part or the mold cavity 11 can be formed from this porous material. This subarea or these sections are delimited by the previously described insert parts 57 from the other components of the blow mold 8, the mold surface 12 of the mold cavity 11 being formed at least in regions in the region of the molded part half 10 by a layer 59 of the porous, in particular air-permeable material, and , as shown here, limited by the two insert parts 57 and a part of the molded part half 10. The layer 59 extends over a thickness which is less than that of the molded part half 10, and in order to be able to suck off the air present between the outer surface 13 of the molded part 2 and the molded surface 12 from this area of the blow mold 8, this layer by at least one, preferably several these associated leads 58, which, starting from this layer 59, penetrate the blow mold 8 and the housing 18 without any flow connection with them, are in flow connection. The derivations 58 can again be connected to a wide variety of vacuum units and, if appropriate, regulating and / or control devices.

Also in the area of the molded part half 9, part of the molded surface 12 in turn forms the layer 59, which can be connected through the one or more derivatives 58 to the same or a further vacuum unit 19 and optionally a regulating and / or control device. The injection lances 16 are arranged in the blow mold 8 in an edge region of the mold cavity or in a part of the mold surface 12 which forms a corner region of the molded part. This is usually directly adjacent to those mold surfaces 12 which face the narrow sides of the molded part, or in one a corner region of the molded part 2 forming part of the molding surface 12. The mold cavity 11 is delimited by two molding surfaces 12 spaced apart from one another and running approximately parallel to one another at a distance between 0.1 and 100 mm, preferably between 0.1 and 20 mm, and these Large-area shaped surfaces are connected to one another by an additional edge around this peripheral edge. The mold cavity is at a distance between two mutually opposite and approximately parallel to each other, which is a slight fraction of the distance between two other, opposing, defining the molding 2 in a different spatial direction.

The injection lance 16 or at least one cannula 43 is alternately via control and / or control valves with a supply line for the gaseous pressure medium and a discharge line for the liquid pressure medium and at least one further cannula is alternately with a discharge line via control and / or control valves the gaseous pressure medium and a feed line for the liquid pressure medium are connected. Irrespective of this, it is also possible to add at least one cannula via control and / or control valves with a feed line for the gaseous or liquid pressure medium and at least one further cannula 43 via control and / or control valves with a discharge line for the gaseous or liquid pressure medium connect.

FIG. 9 shows a further and possibly independent design of the injection lance 16, again using the same reference numerals for the same parts as in FIGS. 4 to 6. This design is similar to that which has already been described in detail in FIG. 6, but in contrast to this the injection lance 16 has a plurality of cannulas, in this case the inner cannula 43 and an outer cannula 60, which are preferably arranged concentrically to one another , having. The cannula 43 can be designed in the same way as that cannula 43 in FIG. 6 and in turn has the channel 45, which is delimited by the cannula wall 46, and ends in the region of the cavity 5 by a conically tapering end 44. It goes without saying but also any other shape of the end 44 is possible and can correspond to one of the configurations previously described in FIGS. 4 to 6.

The additional cannula 60 is aligned with the first cannula 43 approximately concentrically to the longitudinal axis 55 and is likewise designed as a hollow body with a cannula wall 61. One end 62 of this cannula 60 can in turn be conically or conically tapered by the angle 54, starting from the shaped surface 12 in the direction of this end 62, so as to always achieve a tight fit between the penetration opening of the wall part 3 and the cannula 60.

The cannula 43 located here can be shown via a schematically simplified storage arrangement 63 within the outer cannula 60 in the direction of the longitudinal axis 55 relative to the blow mold 8 can be mounted or held. One or more openings 64 can be arranged therein for the passage of the gaseous and / or liquid cooling or pressure medium through this bearing arrangement 63, as a result of which a flow connection between the cavity 5 of the molded part 2 and at least one of the lines 14 or 15 (see FIG. 2 ) can be manufactured. The inner cannula 43 here can also be in flow connection with one of the lines 14, 15, which now makes it possible to supply or remove the gaseous and / or liquid cooling or pressure medium into and from the cavity 5.

For example, one of the pressure or cooling media can be supplied through the inner cannula 43 here and one of these media can be discharged through the cannula 60. However, it is of course also possible to supply the gaseous and / or liquid cooling or pressure medium through the cannula 60 to the cavity 5 and to discharge it again via the cannula 43. Likewise, it can also be advantageous, for example, to supply the liquid cooling or pressure medium via the inner cannula 43 here and to discharge the gaseous cooling or pressure medium through the cannula 60. The same naturally also applies, of course, in the opposite direction and vice versa.

The injection lance 16 shown here in turn also includes the thrust piston 49, which is adjustably mounted or held in the blow mold 8 relative to the latter. In the area of the sealing surface 50 of the thrust piston 49, a recess 51, which is preferably formed around the cannula 60, can in turn be recessed therein and connected to the suction line 52, as a result of which the immediate area of the thrust piston 49 between the sealing surface 50 and the outer surface 13 of the wall part 3, the previously described position fixation can be achieved by a different pressure level.

Finally, it should be mentioned here that the number and arrangement of the injection lances 16 with respect to the cavity 5 has been shown and described only by way of example for a possible molded part 2, but multiple arrangements of the injection lances 16 depending on the volume of the cavity 5 and the flow rate associated therewith can be freely selected as required. A series arrangement of several cannulas 43, 60 in a single thrust piston 49 is also possible, as a result of which a larger inflow and outflow volume of the cooling or pressure media can be achieved in or out of the cavity 5 and can therefore be better coordinated with one another. For the sake of order, it should finally be pointed out that, in order to better understand the structure of the blow mold and the injection lance, these or their components have been shown partially to scale and / or enlarged and / or reduced.

The object on which the independent inventive solutions are based can be found in the description.

Above all, the individual in FIGS. 1; 2; 3; 4, 5, 6; 7; 8 and 9 form the subject of independent, inventive solutions. The relevant tasks and solutions according to the invention can be found in the detailed descriptions of these figures.

Regarding signs

Appendix 41 measuring device

Molding 42 supplementary unit

Wall part 43 cannula

Outer skin 44 end

45 channel cavity

Extruder 46 cannula wall

Extrusion tool 47 breakthrough

Blow mold 48 face

Molded part half 49 thrust piston

Molding half 50 sealing surface

Mold cavity 51 recess

Form surface 52 suction line

Surface 53 distance

Line 54 angle

Line 55 longitudinal axis

Injection lance 56 external dimensions

Pore 57 insert

Housing 58 derivative

Vacuum unit 59 layers

Location 60 cannula

Supply system 61 cannula wall

Pressure generator 62 end

Check valve 63 bearing arrangement

Check valve 64 opening

actuator

pressure generator

supply

actuator

relief means

overflow

storage device

actuator

management

filter element

relief means

return

actuator

measuring element

Claims

Patent claims

1. A method for producing molded parts made of plastic with at least one cavity which is delimited and enclosed by wall parts of an optionally multilayer outer skin, the outer skin being produced continuously or discontinuously in the form of a tube and introduced into a mold cavity of a blow mold at a temperature between the plasticizing temperature and the glass transition temperature the outer skin is at least partially applied to the molded surfaces of the blow mold by building up a pressure difference between the cavity of the molded part and an outer surface thereof, in particular by means of negative pressure, and at least one supply and discharge line between the blow mold and the cavity of the molded part is produced and in at least one cooling or pressure medium is introduced into the cavity of the molded part, characterized in that the air at least in regions between the molded surface of the blow mold and the outer surface of the molded part via pores a porous material that forms the blow mold is suctioned off.

2. A method for producing molded parts made of plastic with at least one cavity which is delimited and enclosed by wall parts of an optionally multi-layer outer skin, the outer skin being produced in a tubular manner continuously or discontinuously and introduced into a mold cavity of a blow mold at a temperature between the plasticizing temperature and the glass temperature the outer skin is at least partially applied to the molded surfaces of the blow mold by building up a pressure difference between the cavity of the molded part and an outer surface thereof, in particular by means of negative pressure, and at least one supply and discharge line between the blow mold and the cavity of the molded part is produced and in at least one cooling or pressure medium is introduced into the cavity of the molded part, characterized in that those wall parts in the region of lead-through openings for the supply of a medium with the negative pressure relative to the molded surface surface are held and fixed, whereupon several injection lances are pushed through them in the areas of the wall parts fixed relative to the molding surface and introduced with their outlet openings into the cavity, whereupon the cavity between 0.01 and 60 sec, preferably between 0.01 and 10 sec , filled with a gaseous medium under excess pressure, the supply and discharge lines closed and the pressure built up in the cavity monitored and that with constant or only minimally, for example at 10% reducing pressure, at least one of the injection lances, a liquid medium with the build-up of excess pressure introduced into the cavity and is conveyed through this, a pressure between 1.5 bar and 50 bar, preferably between 2 bar and 6 bar, being generated by the liquid medium in the cavity.

3. The method according to claim 1 or 2, characterized in that to build up the pressure difference in the cavity of the molded part of one of the pressure media is introduced with a pressure higher than that prevailing between the outer surface of the molded part and the molded surface of the blow mold.

4. The method according to one or more of the preceding claims, characterized in that a cooling or pressure medium is formed by a gas, in particular air.

5. The method according to claim 4, characterized in that a pressure between 1.5 bar and 50 bar, preferably between 2 bar and 7 bar, is built up in the cavity by the gaseous cooling or pressure medium.

6. The method according to one or more of the preceding claims, characterized in that a further cooling or pressure medium is formed by a liquid, in particular water.

7. The method according to one or more of the preceding claims, characterized in that the liquid cooling or pressure medium is cooled to a temperature of below 20 ° C, preferably to 5 ° C, before being introduced into the cavity of the molded part.

8. The method according to one or more of the preceding claims, characterized in that the liquid cooling or pressure medium before introduction into the cavity of the molding to a temperature between -10 ° C and -50 ° C, preferably between -20 ° C and cooled to -40 ° C.

9. The method according to one or more of the preceding claims, characterized in that before the closing of the blow mold in the mold cavity, a further layer is introduced at least in regions and is molded onto the outer surface of the molded part during its final shaping.

10. The method according to one or more of the preceding claims, characterized in that the gaseous and the liquid cooling or pressure medium are introduced into the cavity of the molded part with different flow directions.

11. Injection lance with a cannula for blow molds for the production of molded parts made of plastic with at least one cavity made of prefabricated molded blanks, in which an end facing the mold cavity in the blow mold by means of a drive from a rest position located outside the mold cavity delimited by mold surfaces into an over position this working position projecting into the mold cavity is arranged to be adjustable, characterized in that the cannula (43, 60) has a conically tapering sealing surface or a sealing projection or the injection lance, at least in its partial region projecting from the molding surface (12) into the molding cavity (11) (16) has a thrust piston (49) which is flush with the molding surface (12), through which the cannula (43, 60) projects into the mold cavity (11) and that a front face of the thrust piston (49) surrounding the cannula (43, 60) is used as a Sealing surface (50) between an outer surface (13) of the molded part (2) and the push piston (49) is used.

12. Injection lance according to claim 11, characterized in that the cannula (43, 60) at the mold cavity (11) facing end (44, 62) is closed and on the part adjoining the end (44, 62) of the same radially extending Breakthroughs (47).

13. Injection lance according to claim 11 or 12, characterized in that a plurality of cannulas (43, 60) are arranged on the thrust piston (49), of which at least one with a feed line or a discharge line and / or at least the other with a discharge line or feed line for the cooling or pressure media is connected.

14. Injection lance according to one or more of claims 11 to 13, characterized in that the needles (43, 60) arranged on the thrust piston (49) are each arranged in pairs and concentrically with one another.

15. Injection lance according to one or more of claims 11 to 14, characterized in that at least one cannula (43) via regulating and / or control valves alternately with a feed line for the gaseous cooling or pressure medium and a discharge line for the liquid cooling or pressure medium and at least one further cannula (43) via control and / or control valves are alternately connected to a discharge line for the gaseous cooling or pressure medium and a supply line for the liquid cooling or pressure medium.

16. Injection lance according to one or more of claims 11 to 14, characterized in that at least one cannula (43) via regulating and / or control valves with a feed line for the gaseous or liquid cooling or pressure medium and at least one further cannula (43 ) is connected to a discharge line for the gaseous or liquid cooling or pressure medium via regulating and / or control valves.

17. Blow mold for producing a molded part having at least one cavity from a layer of plastic or a tubular molded part for producing a molded part having a cavity that is completely enclosed to the outside, in which the individual parts of the blow mold are arranged so as to be adjustable relative to one another via drives and in which Blow mold at least two injection lances are adjustably arranged, which are connected from an idle position lying outside the mold cavity formed by the mold surface to an insert position protruding into the mold cavity at least by the thickness of the outer wall of the molded part to be produced, with an adjusting drive for adjustment from the idle position to the insert position, wherein these injection lances have a cannula with a channel for supplying a medium and are connected to a supply system for a medium, in particular a cooling or pressure medium, characterized in that for In some areas, the mold surface (12) of the mold cavity (11) is formed at least by a layer (59) made of porous, in particular air-permeable material, which is arranged in an airtight housing (18) and that the pores (17) of the air-permeable material with a Vacuum unit (19) of a regulating and / or control device are connected.

18. Blow mold according to claim 17, characterized in that the injection lances (16) are arranged in an edge region of the mold cavity (11) or in a corner region of the molded part (2) forming part of the mold surface (12).

19. Blow mold according to claim 17 or 18, characterized in that the injection lances (16) immediately adjacent to those mold surfaces (12) which face the narrow sides of the molded part (2) or in a corner region of the molded part (2) forming part the molding surface (12) are arranged.

20. Blow mold according to one or more of claims 17 to 19, characterized in that the mold cavity (11) by two at a distance between 0.1 and 100 mm, preferably 0.1 to 20 mm, spaced from each other, approximately parallel to each other extending mold surfaces (12) is limited and these are connected to one another via a circumferential edge by further mold surfaces (12).

21. Blow mold according to one or more of claims 17 to 20, characterized in that the mold cavity (11) has a distance between two mutually opposite and approximately mutually parallel mold surfaces (12), which is a slight fraction of the distance between two other, each other opposite, the molding (2) in another spatial direction delimiting molding surfaces (12).

22. Blow mold according to one or more of claims 17 to 21, characterized in that at least a portion thereof is formed by the porous and porous (17) material.

23. Blow mold according to one or more of claims 17 to 22, characterized in that this section is arranged in the region of the injection lance (16).